The invention relates generally to the field of brake systems. Specifically, an electrohydraulic motor vehicle brake system is described. Modern vehicle brake systems operate according to the “brake-by-wire” principle. This means that a hydraulic pressure is built up at the wheel brakes independently of foot force via a hydraulic pressure generator (e.g. a piston-cylinder device with an electromechanical actuator acting on the piston). Brake systems of this kind comprise, apart from the hydraulic pressure generator, a brake pedal interface with a sensor system for detection of an actuation of a brake pedal, a simulator circuit connected to the brake pedal interface for simulation of a realistic pedal response force and a plurality of valves for regulating the pressure. The valves are frequently accommodated in a block-shaped hydraulic control unit. Such brake systems are known, for example, from WO 2006/111393 A1, WO 2012/062393 A1 and WO 2012/152352 A1.
Brake-by-wire brake systems have several advantages. For example, they are ideally suited for the installation of energy recovery systems. Furthermore, a build-up of brake pressure for an individual wheel can be controlled better by such brake systems and vehicle dynamics control programs (ABS, ASR, ESP programs) can be better integrated.
On the other hand, brake-by-wire brake systems comprise a plurality of electrically actuatable hydraulic valves, which are arranged in a complicated network of fluid paths connected to one another. The fluid paths in turn are often only supplied via a central hydraulic fluid reservoir with hydraulic fluid.
The servicing of such brake systems is complex on account of the plurality of valves and fluid guide paths. This is true, for example, of the ventilation of the brake system, as the wheel brakes, the simulator circuit and the hydraulic control unit have to be ventilated separately. The time outlay is correspondingly great in spite of the use of ventilation equipment, such as overpressure or vacuum equipment, for example. In the same way, detection of defective valves or of a leak in the brake system takes a lot of time, as normally all components of the simulator circuit and the brake circuits have to be checked individually in the context of fault location.